Burners for tangentially fired boilers inject the fuel from atomizers in a manner as illustrated in the U.S. Pat. Nos. 4,294,178 and 5,146,858. The liquid fuel burners typically involve the application of the fuel at a very high pressure, of the order of a 1000 psi, and passing the fuel through a back plate into a whirl plate and then through a passage in a spray plate. The whirl plate directs the fuel into a spin so that the fuel emerges into the boiler with a conical pattern. A number of such fuel atomizers are used and direct the fuel tangentially at a centrally located zone where the flame is located.
An atomizer is shown in the U.S. Pat. No. 2,613,112 to Fletcher and illustrates fuel tip or spray plate having an oblong cross section so as to produce a substantially flat spray. The spray plate has an outer conical surface with a solid angle of about 90 degrees. In one embodiment the flat spray is obtained by distributing fuel passages in a diametral plane. This type of spray plate is not suitable for accommodating a highly spun fuel as is used in a tangentially fired boiler.
An electromagnetic fuel injection valve is taught by the U.S. Pat. No. 5,109,824 to Okamoto et al. and shows multiple fuel swirls entering fuel injection port of an engine. In the U.S. Pat. No. 1,569,448 to Ranner liquid fuel from two orifices impact against each other in a substantially flat elongated cavity to form a flat fuel spray. These fuel injection devices are not proposed to reduce NOx in a boiler and do not accommodate a highly spun fuel.
In a copending patent application entitled Internally Air Fuel Staged Flame Stabilizer by Richard J. Monro filed Oct. 27, 1993 bearing Ser. No. 08/144,230, now U.S. Pat. No. 5,415,114 a flame stabilizer is described with which the air flow is circumferentially staged into alternating air lean and air rich zones. The flame stabilizer described in this copending patent application has been in commercial use in connection with the burning of solid fuel for more than a year prior to the filing of the subject patent application.